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Study on Defect Structure and Photorefractive Properties of Lithium Niobate Doped with Ruthenium and Iron

Author: LiuChengLong
Tutor: WangYiJie
School: Harbin University of Science and Technology
Course: Optical Engineering
Keywords: The ruthenium iron lithium niobate Czochralski method. Photorefractive properties Dual-wavelength nonvolatile holographic storage
CLC: O77
Type: Master's thesis
Year: 2010
Downloads: 28
Quote: 0
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Abstract


The optical volume holographic memory for its storage capacity, high data transfer rates, speed of information addressing the advantages of modern storage technology competition shows great advantages and good prospects for development. Lithium niobate crystal because of its good photorefractive properties of a very important volume holographic storage material, but the slow response of lithium niobate, scattering noise readout process volatile shortcomings restricted volume holographic memory development. Therefore, to improve and optimize the lithium niobate crystal, thus improving the overall performance of volume holographic memory has become a prime research topics of the current volume holographic storage field. In this paper, a new double-doped Czochralski method grown macro-defect optical uniformity Ru: Fe: the LiNbO 3 crystals. Ru: Fe: LiNbO 3 crystal structure of intrinsic defects, dopant ions in the crystal placeholder affect the rheological properties of photorefractive crystal. Studied in detail by X-ray, the infrared OH - absorption spectra, and UV - visible absorption spectrum of experimental means, Ru: Fe: LiNbO 3 crystal defect structure and ion placeholder. X-ray diffraction results indicate that, ruthenium iron lithium niobate crystals remain LiNbO 3 original lattice structure of the crystal, the dopant ions substituted Li or Nb manner into the crystal. The lattice constant of pure lithium niobate crystal is slightly larger than the same composition, but due to the dopant ions with different radii of the ions to be substituted, the intensity of diffraction peaks changed. By infrared spectroscopy and UV-visible absorption spectrum analysis to determine the impurity ions Fe and Ru crystal placeholder, the crystal doped ruthenium iron ions occupy the normal Li sites, this form FeLi 2 (FeLi ) and RuLi 3 (RuLi 2 ) defects, by Li vacancies charge compensation. Because the Fe 3 / Fe 2 and Ru 4 / Ru 3 polarization capacity are greater than Li , so that the O 2 - the degree of polarization increases, the deformation of the electron cloud increases will reduce energy electronic transition, causing the red shift of the absorption edge. The oxidation process just change the extent of absorption of the OH-absorption peak, the absorption peak position has not changed, no new absorption peak the oxidation processing the basis of the crystal shift the absorption edge. Through experiments testing different ruthenium content of Ru: Fe: LiNbO 3 crystal light photorefractive performance, including diffraction efficiency, response time, and erase time, dynamic range, and sensitivity. Found that the crystal of ruthenium doping concentration and the oxidation treatment can affect the photorefractive properties of the crystals: With the increase in the concentration of ruthenium in the crystal, the diffraction efficiency of the crystal is increased, response time, dynamic range, increased sensitivity; relative growth state crystals, oxidation treatment makes the diffraction efficiency of the crystals enhanced the response time of growth, the dynamic range, sensitivity decreases. It also found that Ru: Fe: severe asymmetry the LiNbO 3 recording and readout, reflecting Ru: Fe: LiNbO 3 crystal quasi-state non-volatile characteristics. The article also for the first time the use of non-volatile memory technology of dual-wavelength study of Ru: Fe: the LiNbO 3 crystal non-volatile photorefractive properties. Compared to the traditional two-color nonvolatile holographic storage Ru: Fe: the LiNbO 3 crystal dual wavelength non-volatile storage photorefractive performance has been greatly improved.

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CLC: > Mathematical sciences and chemical > Crystallography > Crystal defects
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